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In this paper, a sandwich-type electrochemiluminescent (ECL) immunosensor for detection of microcystin-leucine-arginine (MCLR) based on gold nanoparticles (GNPs) and CdS quantum dots (QDs) was constructed. Transmission electron microscope image (TEM), photoluminescence spectra, ultraviolet-visible absorption spectra were used to characterize the CdS QDs. The fabrication processes of the immunosensor were characterized via electrochemical impedance spectra (EIS). A strong and stable ECL signal was emitted through the electron-transfer reaction between the electron-injected CdS QDs and reduced products of S 2 O 8 2− in phosphate buffered solution (PBS, pH 7.4) containing of 0.1 M K 2 S 2 O 8 and 0.1 M KCl. Under the optimum conditions, the ECL immunosensor possesses a wide linear response to MCLR that ranges from 0.01 to 50 μg/L, with a low detection limit of 0.0028 μg/L. Moreover, selectivity, stability, and reproducibility of the proposed immunosensor were acceptable. [ABSTRACT FROM AUTHOR]

Abstract: A fluorescein derivative, 2-pyridylaldehyde fluorescein hydrazone (FHP), was developed for detection of hypochlorites. This probe functioned by oxidizing Cu+ to Cu2+ to form a Cu2+ complex, which produced colorimetric and fluorescent signals that were monitored by ultraviolet–visible and fluorescence spectrophotometry, respectively. Other common anions, including F−, Cl−, ClO3 −, NO2 −, CN−, S2−, SCN−, P2O7 4−, AcO−, CO3 2−, SO4 2−, ClO4 −, did not interfere with the hypochlorite detection, and hypochlorites could be detected at low micromolar levels in aqueous solutions. The color change on reaction with hypochlorites was rapid and visible to the naked eye. The sensor could be applied to the detection of hypochlorites tap water. [Copyright &y& Elsevier]

A novel electrochemiluminescence (ECL) aptasensor based on CdS–MoS 2 nanocomposites was designed for detection of immunoglobulin E (IgE). The flowerlike CdS–MoS 2 composites were synthesized through a simple one-pot hydrothermal method. The CdS–MoS 2 composites were immobilized on glassy carbon electrode surface as ECL emitter attached a complementary ssDNA (NH 2 –ssDNA) of IgE. IgE aptamer (T-Apt) with DNAzyme–AuNPs can hybridize with NH 2 –ssDNA to form dsDNA. The DNAzyme with horseradish peroxidase-like activity could electrocatalyze the reduction of H 2 O 2 , the coreactant of CdS–MoS 2 ECL emission, leading to an obvious ECL quenching. In the presence of IgE, IgE conjugated with DNAzyme–AuNPs–T-Apt and thereafter the conjugations released, which decreased the consumption of H 2 O 2 by DNAzyme–AuNPs, produced an increased ECL signal. The changed ECL intensity is proportional to concentration of IgE in the range of 0.001–10.0 nM with the detection limit of 0.34 pM ( S / N = 3). The prepared aptasensor has been applied to determination of IgE in human serum samples. The recoveries of IgE in human serum samples are between 83.0% and 108% with the RSD values no more than 3.8%. The developed sensor with CdS–MoS 2 composites and DNAzyme features high sensitivity, good selectivity and wide linear range, suggesting the potential applications in biochemical analysis. [ABSTRACT FROM AUTHOR]

A novel competitive electrochemiluminescence (ECL) aptasensor based on CdSe/ZnS quantum dots (QDs) functionalized MoS 2 modified electrode was developed for sensitive immunoglobulin E (IgE) detection using horseradish peroxidase (HRP) catalyzed biocatalytic precipitation (BCP) for signal quenching. MoS 2 was introduced to load QDs using PDDA as a bridge to form the MoS 2 -QDs composites which were employed as matrix for the immobilization of the complementary DNA (cDNA) of IgE aptamer, then HRP functionalized gold nanoparticles (AuNPs) labeled aptamer (aptamer-AuNPs-HRP) was designed as the signal probe for the aptasensor, the presence of HRP would stimulate the BCP onto the electrode surface for its insulating effect on ECL signal, thereby impairing the ECL emission. In the presence of IgE, the signal probe would capture IgE to form conjugation, released from the electrode accompanying decrease of HRP and increase of ECL intensity. Improved sensitivity is achieved through using the signal probe. This fabricated aptasensor displays a liner range from 0.5 pM to 0.5 nM with a detection limit of 0.18 pM ( S/N = 3). Moreover, eight human sera samples were analyzed with recoveries of 85.0–107.5%. The present strategy provides a promising method for the future development of ECL aptasensor for advanced biochemical analysis. [ABSTRACT FROM AUTHOR]

Abstract: Two new Schiff derivatives with N,N-bis(acetyloxyethyl) amino as end group have been synthesized and studied as possible fluorescence probe for Fe3+ detection. The single-photon and two-photon fluorescence properties of the dyes in the unbound state and in metal ions complexes were investigated. Some quantum yields and TPA cross sections at important points were calculated. At the same time, we investigated the stabilization of two complexes in appropriate time range and calculated the thermodynamic parameters of the complex at 298K. The results showed that two compounds can be used as an efficient fluorescent probes for Fe3+ detection by single-photon excitation (SPE). And the process in forming complex was associated with releasing heat and changing degrees of freedom. Moreover, probe-1 is highly sensitive and selective to detect Fe3+ with two-photon active cross-section of 78GM in Tris–HCl buffer solution at 800nm. We proceeded to examine its potential utility for fluorescence imaging of Fe3+ in living cells. The results suggested that designing probe-1 can be used to detect intracellular Fe3+ by one and two-photon fluorescence imaging. [Copyright &y& Elsevier]